November 13, 2018

Containing the latest Ebola outbreak

Given that outbreaks can grow quickly and exponentially, definitive action is needed now.

The current plan for stopping this outbreak is based on contact tracing (the identification and monitoring of people who were exposed to Ebola-infected individuals for the 21 days during which they may develop infection) and “ring” vaccination (immunizing these contacts and those close to them with an experimental Ebola vaccine). This approach efficiently contained an Ebola outbreak in western DRC just a few months ago but requires a comprehensive and precise understanding of who is infected and who their contacts are — something that necessitates having unimpeded daily access to their communities for months.

That has not been possible this time around: Areas affected by violence have been inaccessible for days at a time. Therefore, while contact tracing and ring vaccination should continue where transmissions can be tracked, mass vaccination of larger portions of populations should be considered in areas where that is not possible such as Beni, which has a population of about 230,000. Expanding vaccinations in this manner could immediately halt the spread of the disease.

While such a mass vaccination sounds ambitious, the World Health Organization (WHO) and others have executed much larger national campaigns in over 40 low-income countries, including DRC, where millions of children were immunized against polio or measles within a single week. These campaigns were also implemented successfully during conflicts in Somalia, Afghanistan, and Liberia.

Though a mass-vaccination effort targets an entire population, it need only reach the proportion required for “herd immunity” — immunizing enough people so that the virus cannot spread. Early studies of the Ebola vaccine found that it might be possible to achieve herd immunity by vaccinating as little as 42% of the population.

To be successful, the mass vaccination effort would require the buy-in of the communities and the Ebola response teams being able to securely access the areas in question for the day or two it would take to immunize everyone. Promisingly, a recent study showed that even communities with high levels of distrust appear to be open to vaccination.

Anthropologists are already on the ground working tirelessly to engage community leaders and armed groups. In areas not amenable to outreach, a neutral “white helmet” security force, ideally drawn from the African Union or other countries without past involvement in the DRC conflict, should be deployed with the sole mission of securing vaccination efforts. It should be made abundantly clear to the population that this force has no allegiance to any political or institutional actors and is there only to deter violence against responders. At the end of the day, communities and militias do not want their loved ones to die from Ebola and would respect such a presence if they were reassured its mission is strictly medical.

Mass vaccination will also require an adequate supply of the Ebola vaccine. Its manufacturer, Merck, has committed to maintaining a supply of 300,000 doses at all times. Doing so could become difficult if vaccination efforts are expanded, but at the current juncture, the number of people who would need to be vaccinated in order to stunt the outbreak still appears to be within the range of existing stockpiles. Nonetheless, production of the vaccine should be increased and the bottlenecks to doing so should be assessed and cleared to ensure an adequate supply.

It’s true that the Ebola vaccine is still experimental and its health risks are not yet fully known. However, for people living in areas where everyone who is infected is not known, the heightened risk of unknowingly contracting a fatal Ebola infection may, at this point, outweigh the potential danger posed by the vaccine.

Comments

Given that outbreaks can grow quickly and exponentially, definitive action is needed now.

The current plan for stopping this outbreak is based on contact tracing (the identification and monitoring of people who were exposed to Ebola-infected individuals for the 21 days during which they may develop infection) and “ring” vaccination (immunizing these contacts and those close to them with an experimental Ebola vaccine). This approach efficiently contained an Ebola outbreak in western DRC just a few months ago but requires a comprehensive and precise understanding of who is infected and who their contacts are — something that necessitates having unimpeded daily access to their communities for months.

That has not been possible this time around: Areas affected by violence have been inaccessible for days at a time. Therefore, while contact tracing and ring vaccination should continue where transmissions can be tracked, mass vaccination of larger portions of populations should be considered in areas where that is not possible such as Beni, which has a population of about 230,000. Expanding vaccinations in this manner could immediately halt the spread of the disease.

While such a mass vaccination sounds ambitious, the World Health Organization (WHO) and others have executed much larger national campaigns in over 40 low-income countries, including DRC, where millions of children were immunized against polio or measles within a single week. These campaigns were also implemented successfully during conflicts in Somalia, Afghanistan, and Liberia.

Though a mass-vaccination effort targets an entire population, it need only reach the proportion required for “herd immunity” — immunizing enough people so that the virus cannot spread. Early studies of the Ebola vaccine found that it might be possible to achieve herd immunity by vaccinating as little as 42% of the population.

To be successful, the mass vaccination effort would require the buy-in of the communities and the Ebola response teams being able to securely access the areas in question for the day or two it would take to immunize everyone. Promisingly, a recent study showed that even communities with high levels of distrust appear to be open to vaccination.

Anthropologists are already on the ground working tirelessly to engage community leaders and armed groups. In areas not amenable to outreach, a neutral “white helmet” security force, ideally drawn from the African Union or other countries without past involvement in the DRC conflict, should be deployed with the sole mission of securing vaccination efforts. It should be made abundantly clear to the population that this force has no allegiance to any political or institutional actors and is there only to deter violence against responders. At the end of the day, communities and militias do not want their loved ones to die from Ebola and would respect such a presence if they were reassured its mission is strictly medical.

Mass vaccination will also require an adequate supply of the Ebola vaccine. Its manufacturer, Merck, has committed to maintaining a supply of 300,000 doses at all times. Doing so could become difficult if vaccination efforts are expanded, but at the current juncture, the number of people who would need to be vaccinated in order to stunt the outbreak still appears to be within the range of existing stockpiles. Nonetheless, production of the vaccine should be increased and the bottlenecks to doing so should be assessed and cleared to ensure an adequate supply.

It’s true that the Ebola vaccine is still experimental and its health risks are not yet fully known. However, for people living in areas where everyone who is infected is not known, the heightened risk of unknowingly contracting a fatal Ebola infection may, at this point, outweigh the potential danger posed by the vaccine.